The catch: I must be allowed to self-host. This is almost impossible to find since everybody seems to rely on 3rd party email services.
Look in my profile to see who I am and why I'd say this, but as a quick summary, I have years of experience and have also helped companies set up autoresponders that do over 1M emails a day, and that's exactly why I say this. It is a clusterf*ck and a rabbit hole a mile deep and a mile wide. Pay the money (or in Mailchimp's case, don't pay any money until you get bigger.) It is worth EVERY penny.
By the way, any good autoresponder (I use Mailchimp and Aweber and like them both for different purposes) will let you easily export/back up contacts, and none of the big companies are going anywhere.
Or do you want to sell your product?
It boils down to that. Spend your time doing what you are GREAT at and what you WANT to do. Are you great at email deliverability? Do you want to spend your time becoming an expert on that? Probably not.
I know how to change the oil in my car. I know how to mow my lawn. I know how to clean toilets. I don't do any of those things because they are a huge waste of my time that is better spent elsewhere. Same thing goes here.
Deliverability is a nightmare (client of mine lost 5 figures, because his admins [at Germany's biggest hosting company] messed up the DNS setup).
There's a reason why there are so many companies doing email delivery as a service (SendGrid, MailGun, Postmark - to name a few)